Rifle settling in?

S

Stats Shooter

New member
I posted this in the semi-auto thread but got no response so maybe you guys will have something to say:

So I had bought a Ruger SR 556 Varmint a few months back. I handload so I began shooting up some 55 gr hornady fmj loads I made a while back for a different gun. They shot OK through this 20" 1:8 twist rifle.... about 1.25 - 1.5 moa but I didn't worry much as that load was a bit customized for my carbine 1:9 twist 3029 fps. Then after about 400 rounds to get comfortable with my setup i made a hand load for it using 62 grain pills and got that load down around .75 moa or so at around 3100 fps.

I bought some federal American eagle 5.56 ball ammo mainly for the brass and just to plink around with and just like my 55 grain hand load it was shooting 1.5 moa or so. I just figured this gun didn't like 55 grain fmj's. But seriously, as if someone had flipped a switch, my 55 grain factory ball ammo went down to 0.25 - 0.5 moa?!? So after a few groups I decided to see if my 55 grain hand loads would print as well and sure enough they were below 1/2 moa as well....and my load I customized for this rifle started shooting 1 jagged hole 5 shot groups!!!!

Now I have been doing this a long time and I have seen some of my bolt guns settle in after a few hundred rounds but not so abruptly or dramatically? And this barrel is chrome lined. I'm not complaining but I want to know why?
 
I'm no expert, but as the barrel gets coated in copper, it will reach kind of an equilibrium. How many rounds down the tube? How aggressive is your cleaning routine? Did you do a "barrel break in?"

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When the accuracy improved, I had about 400-450 rounds down the barrel.
It is chrome lined so I didn't"season" the barrel but I do a sort of wear in routine for semi-auto guns where clean it out of the box to remove excess oil etc. Then fire 20 rounds and do a quick clean to remove any metal shavings. Then about 50-75 rounds and clean to remove any remaining shavings. ....after that it's pretty much cleaned using patches of Montana extreme copper killer ever 250-300 rounds. It's piston driven so don't need to clean the bolt/chamber much. Oh and I use CFE 223 so doubt it's copper fouling.

And no I never removed the receiver from the buffer tube, nor did I mess with the castle nut.

But good suggestions so far. Keep them coming
 
Maybe there was some kind of irregularity in the gun, like a burr of metal in the chamber or barrel that got smoothed out from firing.
 
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